The present invention relates to an apparatus for cutting metal workpieces, particularly metal plates.
Metal cutting machines which employ a laser cutting head are known, wherein the laser cutting head is mounted on a moveable gantry, and so that the laser cutting head may be moved in a predetermined path of travel to cut a sheet metal plate or other product positioned on a table underlying the gantry. Such laser cutting machines are capable of producing very accurate cuts in relatively thin sheet metal plates, at rapid production speeds, but in the case of more thick plates, the production speed is significantly reduced. Also, such laser cutters require a relatively complex system of mirrors and lenses, commonly referred to as "flying optics" to transport the beam from a beam generator to the workpiece, and these mirrors and lenses require constant adjustment and maintenance to keep them performing satisfactorily. In this regard, a slight misalignment of the beam can result in a deterioration of the cut quality. Also, in cases where the required laser beam generator is mounted off the gantry because of its physical size, the complexity of the flying optic system is exacerbated.
A further limitation of the known laser cutting machines is the fact that such machines are not able to readily cut thick metal plates, and they have difficulty cutting reflective metals, such as aluminum.
To alleviate the above-noted limitations and disadvantages of the prior laser cutting machines, U.S. Pat. No. 5,350,879 to Chun suggests a hybrid cutting apparatus which has a laser beam cutting head and a plasma arc cutting head mounted side-by-side on a shuttle carrier plate which may be selectively moved to a single fixed cutting station. The workpiece is mounted on a moveable work table so as to permit contoured cutting of the moving workpiece, either by the laser cutting head or the plasma arc cutting head. Cutting in the plasma arc mode thus permits the efficient cutting of relatively thick workpieces, and provides a degree of flexibility in the types of cutting which can be performed. However, the Chun apparatus requires the workpiece to be moved under the laser or plasma head, which limits the size, thickness, and weight of the workpiece which can be handled.
It is an object of the present invention to provide an improved metal cutting apparatus having a laser beam cutting head and of the type employing both a laser cutting head and a plasma arc cutting head.
It is a more particular object of the present invention to provide a metal cutting apparatus having a laser beam cutting head and which is able to handle large and heavy workpieces, and wherein a highly simplified transport system for transporting the laser beam from the generator to the workpiece is provided.
It is another object of the present invention to provide a metal cutting apparatus having the capability to cut with either a laser beam or a plasma arc, and which is capable of cutting at two locations simultaneously, in separately controllable patterns. Thus, for example, the apparatus can cut two like patterns, or two mirror image patterns.
These and other objects and advantages of the present invention are achieved by the provision of a metal cutting apparatus which comprises a table for supporting a workpiece in a fixed location, and a gantry mounted for back and forth movement across the table in a longitudinal direction. A carriage is mounted to the gantry for back and forth movement across the table in a transverse direction, and a laser cutting head and a plasma arc cutting head are each mounted to the carriage in a side-by-side, parallel relationship. A laser beam generator is mounted on the gantry and a beam transport system is provided for transporting the beam from the generator to the laser cutting head so as to operate the cutting head. Also, a plasma control module is provided for operating the plasma arc cutting head, and the module is operatively connected to the plasma arc cutting head so as to operate the same. A controller is provided for selectively moving the gantry in the longitudinal direction and selectively moving the carriage in the transverse direction, while operating either the laser cutting head or the plasma arc cutting head, so as to cut a workpiece positioned on the table along a predetermined pattern.
In the preferred embodiment, the gantry comprises a pair of transversely separated housings, with a support beam extending transversely therebetween. Also, the laser beam generator is mounted in one of the housings, so that the beam transporting system transports the beam essentially directly in the transverse direction to the laser cutting head. Also in the preferred embodiment, the plasma control module is positioned in one of the housings of the gantry, so as to facilitate its connection to the plasma arc cutting head via a flexible bundle of lines.
In a second embodiment of the invention, the apparatus comprises a second carriage mounted for transverse movement along the support beam, and a second laser cutting head and a second plasma arc cutting head are mounted to the second carriage in a side-by-side relationship. A second laser beam generator and a second plasma control module are mounted to the other housing of the gantry in a manner corresponding to that of the first above-described cutting system. The provision of a second cutting system thus provides the apparatus with the ability to simultaneously cut the workpiece at two locations, in separately controllable patterns, thus increasing the productivity of the apparatus.